This invention relates to compositions and methods for temporarily coloring hair using chemically synthesized or giosynthetic water-soluble melanin.
Naturally-occurring melanin is the pigment that gives hair its color. A general discussion of the properties and chemistry of melanins may be found in Prota, G., "Progress In The Chemistry Of Melanins And Related Metabolites," Med. Res. Reviews, 8:525-56 (1988) and Moncrieff, R. W., Manufacturing Chemist, XXI, 8, 330-34 (August 1950). The gradual loss of melanin, with age, causes hair to turn gray.
Naturally-occurring melanin pigment itself is unacceptable for use in a hair dye composition because it is easily rubbed off the hair and leaves hair feeling rough. In the past, one of the best methods for coloring gray hair involved the use of naturally-occurring melanin precursors (such as 5,6 dihydroxyindole (DHI)) that when combined with an oxidant or a metal salt, form melanin pigments within the hair shaft. See, for example, U.S. Pat. No. 3,194,734 (Seemuller et al.), U.S. Pat. No. 4,808,190 (Grollier et al.), and U.S. Pat. No. 4,888,027 (Grollier et al.). However, the use of these melanin precursors has many disadvantages.
The primary disadvantage is that the haircolors initially produced with melanin precursors are undesirable achromatic colors (cold grays and blacks). Melanin precursor dyed hair must undergo a second treatment step with an oxidant such as hydrogen peroxide to achieve natural chromatic colors (warm yellows, reds, and browns). See, for example, U.S. Pat. No. 3,194,734 (Seemuller et al.). In addition, melanin precursors are expensive and, because they are highly reactive, difficult to work with. The use of melanin precursors also results in undesirable scalp and skin staining.
Furthermore, because melanin precursors penetrate the hair shaft, the haircolors produced using melanin precursors are permanent haircolors. That is, the haircolor must grow out with the hair. Often, consumers prefer to use a temporary haircolor that will wash out after one or two shampoos. However, temporary haircolors are unacceptable to consumers unless they do not fade in sunlight any more than natural haircolor, do not rub off, and do not bleed when in contact with perspiration, rain, or swimming pool water.
Therefore, there exists a need in the art for a composition that produces, in a single treatment step, temporary natural-looking haircolor that will not fade substantially in sunlight, will not rub off, and will not bleed when in contact with water; is inexpensive; will not stain skin; and is simple to work with. Applicants have surprisingly found an aqueous composition, which comprises chemically synthesized or biosynthetic water-soluble melanin and at least one water dispersible cationic material, that has each of those characteristics.